Tool-steel.



JESSE ii. DARKE, or LYNN,

MASSACHUSETTS, ASSIGNOR TO GENERAL ELECTRIC COMPANY,

A CORPORATION OF NEW YORK.

TOOL-STEEL.

To all whom it'may concern:

3e it, known that 1, Jesse M. DARKE, a citizen of the United States,residing at Lynn,

county of Essex, State of Massachusetts,

ence of manganese in relatively high percenta e, by the low carboncontent, and by the re ativelyflow chromium content. For certainpurpq'ses vanadium may be present in small percentage.

The process whereby this improved product is roduced differs from priorpractice and is ereinafter set forth in 'suflicient detail to enablepersons skilled in the art to compound the steel.

Asa basis for the steel, I prefer to use Swedish muck-bar,ferro-tungsten and ferrochromium. The ferro-tungsten may be of thevariety now being produced by the electric furnace process and maycontain about 67% tungsten and little or no carbon. The ferro-chromiummay also be of the electric furnace variety, lowin carbon and containingsay 68% chromium. I prefer to use sufficient ferro-tungsten to give thefinished steel about 13.5 per cent. tungsten, though the percentageoftungsten may bevaried somewhat above or below this value as in thechrome-tungsten steels now commonly designated as high-speed steels."lhe ferrochromium is used in relatively small quantity, and thepercentage ofchromium in the steel is kept lower than one-half of oneper cent. As previously stated, the carbon content is loW, preferablyless than one-half of one per cent. in the finished steel.

The components above mentioned may be melted in a crucible in the usualway. Or dinarily these materials, during fusion, yield a slag whichfloats on the top and protects the. steel. If for any reason the (011iponents are too dry to produce slag. I add a certain amount of slag tothe crucible according to common practice. When the steel isSpecification of Letters Patent.

Application filed April 27, 1907.

Patented April 27, 1909.

Serial No. 370,575.

nearly ready for pouring, I introduce sufficient manganese to yield afinished steel having approximately 3% manganese. Some variation in themanganese content is permissible, but the quantity should not be greaterthan 3.25% nor less than 2%. 1 prefer to introduce this manganese as uremetal, or at least in a form substantial y or entirely free from carbon.The manganese now commercially produced by the Goldschmidt Thermitprocess is substantially free from carbon and is quite suitable for useaccordin to my invention.

Ast he protective layer of slag in the crucible has a great chemicalaffinity for manganese, special means must be resorted to forintroducing the manganese into the steel. 1 find that this step can besuccessfully effected by introducing a tube of iron, steel'or othersuitable material through the top' of the furnace and into the crucibleuntil the end of the tube is well below the layer of slag, and thenintroducing the manganese through the tube. The manganese may be inlumps the size of a walnut and will pass through the tube into the steelwith very little loss by slagging. After the manganese is introduced,the crucible may remain in the fire for about five minutes and may thenbe poured in the usual way.

The steel resulting from, the above described process may be hardenedlike other air hardening steels and is suitable for cutting tools. Likethe alloy steels relatively high in chromium, it may be used for heavycuts at high speed. The tools retain their cutting edge at hightemperatures much better than carbon steels, and are in other ways wellsuited for heavy duty.

For certain purposes I may introduce a certain quantity of vanadium intothe steel, say in the proportion of about one-fourth of one er cent.This vanadium increases the re hardness and enables the tool to stand ubetter when taking a heavy cut or chip; w at is more important, itprevents the chi p from sticking to the point of the tool. Jhe vanadiummay be introduced'in any suitable form, as by including ferrovanadiumwith the Swedish mucker and other components of the original charge,

The novel features of the process of manufacture are not herein claimedas these form the subject-matter'of a divisional application Serial No.424,054, filed March 30, 1908.

What I claim as'new and desire to secure inately 13.5% tungsten andapproximately 15 3% manganese.

5. At0ol steel containing approximately 13.5% tungsten, less thanone-half of 1% chromium, approximately 3% manganese, and approximatelyone-fourth of 1% vana- 20 dium. In witness whereof, I have hereuntosetmy hand this 25th day of April, 1907.

JESSE DARKE.

Witnesses:

BENJAMIN B. HULL, HELEN ORFORD.

